docs: def get_context_data(self,**kwargs):
          ''' Add the event and series listing data '''
          context = self.get_listing()
          context['showDescriptionRule'] = getConstant('registration__showDescriptionRule') or 'all'
          context.update(kwargs)
  
          # Update the site session data so that registration processes know to send return links to
          # the registration page.  set_return_page() is in SiteHistoryMixin.
          self.set_return_page('registration',_('Registration'))
  
          return super(ClassRegistrationView,self).get_context_data(**context)